Subjectivity in Selecting Events

In addition to limitations in the types of causality considered, the causal factors identified using event-chain models depend on the events that are considered and on the selection of the conditions that link the events. Other than the physical events immediately preceding or directly involved in the loss, however, the choice of events to include is subjective and the conditions selected to explain the events is even more so. Each of these two limitations is considered in turn. 

The selection of events to include in an event chain is dependent on the stopping rule used to determine how far back the sequence of explanatory events goes. Although the first event in the chain is often labeled the initiating event or root cause, the selection of an initiating event is arbitrary and previous events and conditions could always be added. 

Sometimes the initiating event is selected (the backward chaining stops) because it represents a type of event that is familiar and thus acceptable as an explanation for the accident or it is a deviation from a standard [166]. In other cases, the initiating event or root cause is chosen because it is the first event in the backward chain for which it is felt that something can be done for correction.  

The backward chaining may also stop because the causal path disappears due to lack of information. Rasmussen suggests that a practical explanation for why actions by operators actively involved in the dynamic flow of events are so often identified as the cause of an accident is the difficulty in continuing the backtracking through a human [166]. 

A final reason why a root cause may be selected is that it is politically acceptable as the identified cause. Other events or explanations may be excluded or not examined in depth because they raise issues that are embarrassing to the organization or its contractors or are politically unacceptable. 

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